Go over to the Dollar Store and buy a pack of Popsicle sticks. Raise the hood about 18", look at the spring from the side of the car close to the hinge, coils should now start separating. Prop the hood up to keep it from accidentally closing. Start inserting the sticks in between the coils insert as many as you can , hood can always be lifted slightly to obtain better coil spread. Remove the hood prop and start to put the hood down, best if you have a helper but can be done by yourself with shorter hood prop. Always insure that hood will not slam down. Go around to the hinge, reach in and grab onto the spring, as the coils can not longer retract because of the stick spacers the spring coil remains longer and now becomes loose, then remove off the hinge.
To replace with a new spring the use of a floor jack is required. Loop one end of the spring onto the axle at the front of the jack and place the other end onto the lift plate. Start jacking, the spring will now start spreading. Again, place Popsicle sticks between the coils, try to fill most of the coils. Slowly release the jack and spring will now come loose with the sticks stuck between the coils. You should now be able to replace the new spring onto the hinge. Once installed raise the hood and the spring will now start to stretch, sticks will loosen and fall out. Some folks use large washers but I find the sticks will not cause any paint damage when they fall onto the inner fender.
Used this method on two of my cars a few years back and worked well.